1. Field of the Invention
The present invention relates to a printed circuit board(PCB) flat level compensating unit of a surface mounting apparatus in which when a PCB is stopped at its working position and is firstly pushed up from the lower portion thereof, the PCB is secondly pushed to be raised thereby to be compensated its flat level and the mounting height for the PCB according the thickness is adjusted thereby to be increased an amounting efficient and a precision
2. Description of the Prior Art
It has been developed rapidly an electric and electronic products for directing high density, small size and variety. Especially, it has been accelerated a surface mounting technology using a surface mounting apparatus for manufacturing a Printed Circuit Board(PCB).
The surface mounting apparatus is very important constituting the surface mounting assembly apparatus for mounting a surface mounting device to the PCB and is supplied with the surface mounting device from a device supplier thereby to feed to a mounting position on the PCB and mounts it on the PCB.
The surface mounting apparatus can be divided into a high-speed apparatus and a general-use apparatus by function. The high-speed apparatus can accomplish the high-speed mounting operation because it is constructed to assembly many devices in a short time. Therefore, it has a merit that it comply with a mass production, however, its mounting precision become deteriorated.
Meanwhile, the general-use apparatus can accomplish a high-precision because it is constructed to comply with many devices. Therefore, it has a merit that it comply with a medium, small production, however, a productivity become deteriorated because of a low-speed mounting operation.
The surface mounting apparatus comprises a feeder (referring to xe2x80x9ca tape feederxe2x80x9d as below) for supplying a device to be mounted, a X-Y gantry for determining a working position, a conveyor for carrying a PCB to be worked, and a head for picking up, in regular sequence, the device from the feeder for mounting the device on the PCB.
In general, the surface mounting apparatus serves to mount an electronic device on the PCB and can be called a mounter.
More detailed structure for the mounter is as follows.
The mounter comprises; a base assembly; a conveyor installed at the upper portion of the base assembly for feeding a printed circuit board; a feeder for supplying a device or a chip so that the PCB is supplied with the device to be mounted; a monitor head assembly for mounting each device being supplied from the feeder; a vision part for acknowledging and correcting the position of the device; and a X-Y gantry installed with the vision part and the mounter head for determining the position by the table.
The head part comprises a suction nozzle for directly sucking the device, a nozzle chuck for fixing the sucked device, and a nozzle exchanging unit for exchanging the nozzle.
The conveyor is for feeding the PCB to be mounted various chips. When the PCB is fed by the conveyor belt installed at the conveyor the stopping unit is contacted with one side of the PCB to be stopped at the working position so that the mounter head can mount the chip.
When the PCB is stopped its movement, the PCB is ascended by the compensating unit to be contacted with the rail., Therefore, the chip is correctly mounted.
The PCB has a self-distortion to be burgled in the upper direction or to be dented in the lower direction according to 0.4 mm to 4.0 mm of thickness thereof when the PCB is supplied to the conveyor.
This phenomenon is occurred at the initial stage of PCB manufacturing process. Therefore, it cannot be constantly kept a flat level for the PCB.
To compensating the distortion of the PCB like that, it is used the method that the PCB is pushed from the lower portion thereof by the pin or is sucked to be compensated its flat level thereby to be constantly kept its thickness.
However, the conventional PCB should be necessary with the independent compensating unit for compensating the flat level because it is raised to the mounting height without being controlled when the PCB is ascended for mounting the device thereon after the PCB is stopped at its working position.
Although some apparatuses use the method that the PCB is pushed from the lower portion thereof by the pin because it is difficult to control its position, the device can not be easily mounted on the PCB.
That is, when the PCB is excessively pushed in the upper direction it is difficult to mount the device on the PCB. Furthermore, various electronic devices or differential kinds of devices can not be continuously mounted on the PCB by the same apparatus.
Further, because the height of the device to be mounted is different each other the error for position can not be prevented thereby causing the device to be broken or be deformed. Therefore, a reliability for a produced good became deteriorated.
Therefore, the present invention has been invented to solve the above problems, it is an object to provided a printed circuit board flat level compensating apparatus of a surface mounting apparatus in which when a PCB is stopped at its working position and is firstly pushed up from the lower portion thereof, the PCB is secondly pushed to be raised thereby to be compensated its flat level and the mounting height for the PCB according the thickness is adjusted thereby to be increased an amounting efficient and a precision.
To accomplish the above object the present invention provides a PCB flat level compensating unit of a surface mounting apparatus comprising: a base; first moving means disposed at the center portion of the base for moving in left and right direction; transfer means installed at a bracket secured to the first moving means; driving means installed at the transfer means; adjusting means installed at the lower portion of the base and connected to the first moving means; second moving means for moving the adjusting means; and at least one compensating means installed at the base for pushing and sucking the PCB to compensate the distortion of the PCB.